Oxygen deprivation induced cell death: an update

Mammalian cells have multiple responses to low or zero oxygen concentrations. In the complete absence of oxygen, cells undergo cell death through apoptosis, and not necrosis. Apoptotic signaling during oxygen deprivation occurs through the release of cytochrome c and apaf-1 mediated caspase-9 activation. The upstream regulators of cytochrome c release are the Bcl-2 family members. Pro-apoptotic Bcl-2 family members such as bax or bak are clearly required to initiate cytochrome c/apaf-1/caspase-9 mediated cell death during oxygen deprivation. Here we review what is currently known oxygen deprivation induced cell death and speculate about initiating mechanisms resulting in the activation of pro-apoptotic Bcl-2 family members.     

Hexokinase-mitochondria interaction mediated by Akt is required to inhibit apoptosis in the presence or absence of Bax and Bak

The serine/threonine kinase Akt inhibits mitochondrial cytochrome c release and apoptosis induced by a variety of proapoptotic stimuli. The antiapoptotic activity of Akt is coupled, at least in part, to its effects on cellular metabolism. Here, we provide genetic evidence that Akt is required to maintain hexokinase association with mitochondria. Targeted disruption of this association impairs the ability of growth factors and Akt to inhibit cytochrome c release and apoptosis. Targeted disruption of mitochondria-hexokinase (HK) interaction or exposure to proapoptotic stimuli that promote rapid dissociation of hexokinase from mitochondria potently induce cytochrome c release and apoptosis, even in the absence of Bax and Bak. These effects are inhibited by activated Akt, but not by Bcl-2, implying that changes in outer mitochondrial membrane (OMM) permeability leading to apoptosis can occur in the absence of Bax and Bak and that Akt inhibits these changes through maintenance of hexokinase association with mitochondria.     

Biodelignification of lignocellulose substrates: An intrinsic and sustainable pretreatment strategy for clean energy production

Lignocellulosic biomass (LB) is a promising sugar feedstock for biofuels and other high-value chemical commodities. The recalcitrance of LB, however, impedes carbohydrate accessibility and its conversion into commercially significant products. Two important factors for the overall economization of biofuel production is LB pretreatment to liberate fermentable sugars followed by conversion into ethanol. Sustainable biofuel production must overcome issues such as minimizing water and energy usage, reducing chemical usage and process intensification. Amongst available pretreatment methods, microorganism-mediated pretreatments are the safest, green, and sustainable. Native biodelignifying agents such as Phanerochaete chrysosporium, Pycnoporous cinnabarinus, Ceriporiopsis subvermispora and Cyathus stercoreus can remove lignin, making the remaining substrates amenable for saccharification. The development of a robust, integrated bioprocessing (IBP) approach for economic ethanol production would incorporate all essential steps including pretreatment, cellulase production, enzyme hydrolysis and fermentation of the released sugars into ethanol. IBP represents an inexpensive, environmentally friendly, low energy and low capital approach for second-generation ethanol production. This paper reviews the advancements in microbial-assisted pretreatment for the delignification of lignocellulosic substrates, system metabolic engineering for biorefineries and highlights the possibilities of process integration for sustainable and economic ethanol production.     

Effect of Solarization and Nematicidal Treatment of Nursery Beds and Summer Ploughing of Main Field on Root-Knot Nematodes and Performance of Rice Crop*

The reduction in nematode population levels achieved by soil solarization and nematicides in nursery beds resulted in significantly improved health of the rice seedlings which when transplanted in the main field gave better control in treated and untreated in the main field. Application of nematicides phorate or carbofuran after soil solarization gave greater reduction in nematode infection and increased weight. However, soil solarization had the major influence. Further application of the nematicides in the solarized main field gave 53.2% higher yield over untreated control which was only 3.8% higher than that from untreated main field. Soil solarization could be a practical, feasible and environmentally safer alternative to nematicides.